1. Field of the Invention
This invention relates to a flow balanced turbine power plant and, more specifically, to a flow balanced integrated gasification combined cycle gas turbine power plant which utilizes the full power of the gas turbine power plant""s compressor.
2. Background Information
Gas turbine power plants typically include three primary assemblies: a compressor assembly, a combustor assembly, and a turbine assembly. A flow path exists through these assemblies. The turbine assembly is mechanically coupled to the compressor assembly by a central shaft. The power plant further relies on a fuel delivery system and may rely on a steam system for cooling steam or other purposes. In operation, the compressor compresses ambient air and directs the compressed air through the flow path to the combustor assembly. In the combustor assembly, the compressed air is combined with a fuel and ignited thereby creating a working gas. The working gas passes further down stream in the flow path to the turbine assembly. In the turbine assembly the working gas is expanded creating a rotational force in the shaft. The shaft is coupled to a generator and to the compressor assembly. The shaft drives both the compressor assembly and the generator.
Governmental air pollution standards currently limit the level of emission of pollutants from fossil fuel fired power plants. Fossil fuels produce particulate matter, NOx emissions and have a high sulfur content. Instead of burning fossil fuels, a power plant may use a synthetic fuel such as the synthetic fuel produced from the gasification of coal. Generally speaking, coal gasification creates a synthetic gas by reacting coal, oxygen and steam to produce a gas containing carbon monoxide and hydrogen. The synthetic fuel is suitable for use as a fuel gas.
While the synthetic fuel may be used as a fuel gas, its heating value is approximately ⅕th to {fraction (1/10)}th of the heating value of natural gas depending on the feed stock used for fuel. Thus, the mass flow of fuel to the combustor assembly and the turbine assembly of the power plant is five to 10 times as great as for natural gas. The turbine assembly is limited to the amount of mass flow that it can accept and, thus, the compressor air intake has to be decreased to adjust for the mass flow mismatch. Although the output of the power plant is generally greater as a result of the increased mass flow, the output of the total integrated gasification combined cycle system can be further increased by utilizing the full air input of the power plant compressor. An integrated gasification combined cycle gas turbine power plant is disclosed in U.S. Pat. No. 5,079,909, which is assigned to the assignee of this application.
There is, therefore, a need for a flow-balanced gas turbine having an integrated gasification combined cycle system which fully utilizes the compressed air from the power plant""s compressor.
There is a further need for a flow-balanced gas turbine arrangement that can be incorporated in present integrated gasification combined cycle systems.
These needs, and others, are met by the invention which provides a system having two integrated power plants; a primary power plant and a secondary power plant. The compressor assembly of the primary power plant is coupled to the compressor assembly and combustor assembly of the secondary power plant. The secondary compressor directs compressed air to the gasifier assembly where the compressed air aids in the manufacture of the synthetic gas. The gasifier assembly is in fluid communication with the both the primary and secondary combustor assemblies and provides synthetic fuel thereto. The combustor assemblies receive the synthetic fuel from the gasifier and compressed air from the primary compressor assembly. The fuel and the compressed air are mixed and ignited in each combustor assembly thereby creating a working gas. The working gas in the primary combustor assembly is expanded through the primary turbine assembly, the working gas in the secondary combustor assembly is expanded through the secondary turbine assembly. Each turbine assembly has a central shaft coupled to their respective compressor assembly and a generator. Rotation of the central shaft drives the compressor assemblies and the generator assemblies.
The flow balanced gas turbine power plant further includes a steam system which provides steam to the gasifier and may provide cooling steam to various components. The steam system may include a heat recovery steam generator located in the exhaust path of the primary turbine assembly and/or the secondary turbine assembly. Water is provided to the heat recovery steam generator which converts the water to steam. The steam is delivered to the gasifier assembly and, if excess steam exists, may be directed to a steam power plant.